Effects of small intestinal submucosa (SIS) on the murine innate immune microenvironment induced by heat-killed Staphylococcus aureus

Tissue Engineering Neovagina for Vaginoplasty in Mayer-Rokitansky-Küster-Hauser Syndrome and Gender Dysphoria Patients: A Systematic Review

Background: Vaginoplasty is a surgical solution to multiple disorders, including Mayer-Rokitansky-Küster-Hauser syndrome and male-to-female gender dysphoria. Using nonvaginal tissues for these reconstructions is associated with many complications, and autologous vaginal tissue may not be sufficient. The potential of tissue engineering for vaginoplasty was studied through a systematic bibliography search. Cell types, biomaterials, and signaling factors were analyzed by investigating advantages, disadvantages, complications, and research quantity. Search Methods: A systematic search was performed in Medline, EMBASE, Web of Science, and Scopus until March 8, 2022. Term combinations for tissue engineering, guided tissue regeneration, regenerative medicine, and tissue scaffold were applied, together with vaginoplasty and neovagina. The snowball method was performed on references and a Google Scholar search on the first 200 hits. Original research articles on human and/or animal subjects that met the inclusion (reconstruction of vaginal tissue and tissue engineering method) and no exclusion criteria (not available as full text; written in foreign language; nonoriginal study article; genital surgery other than neovaginal reconstruction; and vaginal reconstruction with autologous or allogenic tissue without tissue engineering or scaffold) were assessed. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist, the Newcastle-Ottawa Scale, and the Gold Standard Publication Checklist were used to evaluate article quality and bias. Outcomes: A total of 31 out of 1569 articles were included. Data extraction was based on cell origin and type, biomaterial nature and composition, host species, number of hosts and controls, neovaginal size, replacement fraction, and signaling factors. An overview of used tissue engineering methods for neovaginal formation was created, showing high variance of cell types, biomaterials, and signaling factors and the same topics were rarely covered multiple times. Autologous vaginal cells and extracellular matrix-based biomaterials showed preferential properties, and stem cells carry potential. However, quality confirmation of orthotopic cell-seeded acellular vaginal matrix by clinical trials is needed as well as exploration of signaling factors for vaginoplasty. Impact statement General article quality was weak to sufficient due to unreported cofounders and incomplete animal study descriptions. Article quality and heterogenicity made identification of optimal cell types, biomaterials, or signaling factors unreliable. However, trends showed that autologous cells prevent complications and compatibility issues such as healthy cell destruction, whereas stem cells prevent cross talk (interference of signaling pathways by signals from other cell types) and rejection (but need confirmation testing beyond animal trials). Natural (orthotopic) extracellular matrix biomaterials have great preferential properties that encourage future research, and signaling factors for vascularization are important for tissue engineering of full-sized neovagina.

Development and Characterization of an Acellular Porcine Small Intestine Submucosa Scaffold for Use in Corneal Epithelium Tissue Engineering

Purpose: To produce an acellular small intestine submucosa (SIS) that would be a suitable scaffold for corneal epithelium tissue engineering.Methods: The SIS was decellularized by immersion in 0.1% (wt/vol) sodium dodecyl sulfate (SDS). The efficacy of acellularization was confirmed by histological observation and DNA quantification. The mechanical properties were evaluated by uniaxial tensile testing. ELISA was performed to assess the growth factor contents. The cytotoxicity of SIS scaffolds and extracts to rabbit corneal epithelial cells was determined by CCK-8 assay. We also investigated the inflammatory reaction of SIS implanted subcutaneously in a rat. The biocompatibility was studied by rabbit interlamellar corneal transplantation and reseeding assay with cornea-derived cells. Immunofluorescent staining was used to detect the expression of CK3, ZO-1 and K13.Results: Histological analyses showed that complete cell removal was achieved, and the DNA quantity, which reflects the presence of cellular materials, was significantly diminished in acellular SIS. Collagen fibers were properly preserved and appeared in an orderly fashion. The tissue structure, the mechanical properties and the growth factor contents within the acellular SIS were well retained. The CCK8 assay demonstrated that the acellular SIS scaffolds and extracts had no cytotoxicity to rabbit corneal epithelial cells. There was no sign that an immune reaction occurred with acellular SIS implanted subcutaneously in a rat. In fact, in vivo implantation to rabbit interlamellar stromal pockets showed good biocompatibility. We also observed that clusters of rabbit corneal epithelial cells were growing well on the surface of the SIS in vitro and the distinctive CK3, ZO-1 for corneal epithelial cells was detected.Conclusions: The decellularized SIS retained the major structural components. The matrix is biocompatible with cornea-derived cells and might be a suitable scaffold for corneal epithelium tissue engineering.

Umbilical cord-derived mesenchymal stem cell transplantation in vaginal replacement in vitro and in a rat model

Cell transplantation strategies represent a potential therapeutic approach towards repair of congenital vaginal agenesis. In this study, the efficacy and mechanisms of action of treatment with human umbilical cord-derived mesenchymal stem cells (UC-MSCs) on vaginal regeneration was explored. UC-MSC transplantation alone, small intestinal submucosal (SIS) grafting alone, and a combination of UC-MSC transplantation/SIS grafting were performed with a vaginal defect rat model. Histological analyses of tissue sections were subsequently performed. UC-MSCs promoted the recovery of keratinizing squamous epithelium and papillae to nearly the same levels as in normal tissue. Of the treatments tested, UC-MSC transplantation showed optimal performance in inhibiting collagen deposition and accelerating the synthesis of elastin to maintain tissue elasticity. UC-MSC treatment also increased Cyclin D1, Ki67, and CD31 expression as assessed by immunohistochemistry. We also investigated the effects of UC-MSC secretions on keratinocytes in a co-culture model. UC-MSCs significantly stimulated vaginal tissue repair by promoting vaginal epithelium regeneration via paracrine factors but not by exploiting their keratinocyte differentiation potential. Further, UC-MSCs facilitated epithelial cell viability and promoted cell cycle progression via the AKT/GSK3β/Cyclin D1 pathway. These results indicate that UC-MSC transplantation is a feasible approach for vaginal tissue regeneration.

The use of small intestinal submucosa graft for hypospadias repair: Pilot study

Objective

To evaluate the outcome of using commercially available (SIS) grafts for repairing hypospadias. Collagen-based acellular matrices, including SIS and bladder submucosa matrix, have been used to repair urethral strictures, with varying success, and patients with hypospadias and with inadequate or no genital skin need a substitute tissue for urethroplasty.

Patients and methods

This pilot study included 12 patients (mean age 8 years, range 1.5–15) with hypospadias (distal in six, mid-shaft in four and proximal in two). They underwent a repair with four layers of prefabricated SIS as an onlay graft. The outcome was assessed for cosmetic appearance, urinary stream and the postvoid residual volume. The chi-squared and Mann–Whitney U-tests were used to assess the relationship between preoperative factors and the outcome of the repair with SIS grafting.

Results

The mean (range) follow-up was 23 (6–36) months. Nine patients ultimately voided normally, with a good cosmetic appearance and no postvoid residual urine. Six patients had a successful repair with no further intervention, whilst three had small fistulae that were treated by simple closure. In three patients the graft failed, by complete disruption or stricture. Graft infection adversely affected the outcome of SIS grafting.

Conclusions

The prefabricated SIS graft can be used as an alternative substitute for urethral reconstruction when genital skin is insufficient or lacking, as in circumcised patients or a repeat hypospadias repair. Graft infection is the chief reason for graft failure and should be prevented. Further studies with more patients are needed to confirm these preliminary results.